sedimentary

Jasper

Agate/Jasper (Microcrystalline Quartz, SiO2)

Hardness: 6.5–7 on Mohs scale. Color: Opaque reddish-orange to tan due to iron inclusions. Luster: Vitreous to waxy. Crystal Structure: Trigonal/Microcrystalline. Cleavage: None (conchoidal fracture).

Hardness: 6
Color: Opaque reddish-orange to tan due to iron inclusions
Luster: Vitreous to waxy

Identified April 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from silica-rich fluids depositing in cavaties or replacing organic matter/other minerals within volcanic or sedimentary environments. This specimen appears river-tumbled and water-worn, potentially dating from the Mesozoic or Cenozoic eras depending on local geology.

Uses & applications

Used primarily in lapidary work for cabochons, beads, and tumbled stones. Also used in industrial grinding media and for decorative gravel.

Geological facts

The word 'Jasper' comes from the Greek 'iaspis', meaning 'spotted stone.' It is a member of the chalcedony family and its color is highly dependent on the oxidation state of iron impurities within the silica matrix.

Field identification & locations

Identify in the field by its smooth, water-worn surface, opacity (light generally does not pass through, unlike agate), and its ability to scratch glass. Commonly found in riverbeds, gravel pits, and desert washes throughout the Western United States and worldwide.

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